TY - JOUR
T1 - Involvement of Munc18 isoforms in the regulation of granule exocytosis in neutrophils
AU - Brochetta, Cristiana
AU - Vita, Francesca
AU - Tiwari, Neeraj
AU - Scandiuzzi, Lisa
AU - Soranzo, Maria Rosa
AU - Guérin-Marchand, Claudine
AU - Zabucchi, Giuliano
AU - Blank, Ulrich
N1 - Funding Information:
We are grateful to Dr Cécile Pouzet (IFR-02, Paris-Nord) for her precious help in confocal analysis. We thank Dr. R. Menegazzi (University of Trieste) for providing rabbit anti-MPO. We thank Miss Chiara Bulfon for counting gold-particles in electron mycroscopy analysis and Mr. Claudio Gamboz for technical assistance and helpful experience in ultrathin sections preparation. This research project has been supported by FRM, from the “Association pour l’Utilisation du Rein Artificiel” and a Marie Curie Early Stage Research Training Fellowship of the European Community’s Sixth Framework Programme under contract number 504926.
PY - 2008/10
Y1 - 2008/10
N2 - Human neutrophil granule exocytosis mobilizes a complex set of secretory granules. This involves different combinations of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins to facilitate membrane fusion. The control mechanisms governing the late fusion steps are still poorly understood. Here, we have analyzed SNARE-interacting Sec1/Munc18 (SM) family members. We found that human neutrophils express Munc18-2 and Munc18-3 isoforms and that Munc18-2 interacts with the target-SNARE syntaxin 3. Munc18-2 was associated preferentially with primary granules but could also be found with secondary and tertiary granules, while Munc18-3 was majorily associated with secondary and tertiary granules. Ultrastructural analysis showed that both Munc18-2 and Munc18-3 were often located in close proximity to their respective SNARE-binding partners syntaxin 3 and syntaxin 4. Both isoforms were also found in plasma membrane fractions and in the cytosol, where they associate with cytoskeletal elements. Upon stimulation, Munc18-2 and Munc18-3 redistributed and became enriched on granules and in the plasma membrane. Munc18-2 primary granule exocytosis can be blocked by introduction of Munc18-2-specific antibodies indicating a crucial role in primary granule fusion. Our results suggest that Munc18-2 acts as a regulator of primary granule exocytosis, while Munc18-3 may preferentially regulate the fusion of secondary granules.
AB - Human neutrophil granule exocytosis mobilizes a complex set of secretory granules. This involves different combinations of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins to facilitate membrane fusion. The control mechanisms governing the late fusion steps are still poorly understood. Here, we have analyzed SNARE-interacting Sec1/Munc18 (SM) family members. We found that human neutrophils express Munc18-2 and Munc18-3 isoforms and that Munc18-2 interacts with the target-SNARE syntaxin 3. Munc18-2 was associated preferentially with primary granules but could also be found with secondary and tertiary granules, while Munc18-3 was majorily associated with secondary and tertiary granules. Ultrastructural analysis showed that both Munc18-2 and Munc18-3 were often located in close proximity to their respective SNARE-binding partners syntaxin 3 and syntaxin 4. Both isoforms were also found in plasma membrane fractions and in the cytosol, where they associate with cytoskeletal elements. Upon stimulation, Munc18-2 and Munc18-3 redistributed and became enriched on granules and in the plasma membrane. Munc18-2 primary granule exocytosis can be blocked by introduction of Munc18-2-specific antibodies indicating a crucial role in primary granule fusion. Our results suggest that Munc18-2 acts as a regulator of primary granule exocytosis, while Munc18-3 may preferentially regulate the fusion of secondary granules.
KW - Exocytosis
KW - Neutrophils
KW - SM proteins
KW - SNARE
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U2 - 10.1016/j.bbamcr.2008.05.023
DO - 10.1016/j.bbamcr.2008.05.023
M3 - Article
C2 - 18588921
AN - SCOPUS:50849129555
SN - 0167-4889
VL - 1783
SP - 1781
EP - 1791
JO - Biochimica et Biophysica Acta - Molecular Cell Research
JF - Biochimica et Biophysica Acta - Molecular Cell Research
IS - 10
ER -